Feb 6 (Reuters) - A key safety system was turned off on

a U.S. Army helicopter that collided with an American Airlines ( AAL )

regional jet last week near Washington Reagan Airport,

killing 67.

Senate Commerce Committee chair Ted Cruz told reporters the

Black Hawk helicopter had turned off its automatic dependent

surveillance-broadcast (ADS-B), which is permitted for military

aircraft.

"This was a training mission, so there was no compelling

national security reason for ADS-B to be turned off," Cruz said.